Detergent compositions manufactured in the form of compacted detergent powder are known. U.S. Pat. No. 5,225,100, for example, describes a tablet of compacted powder comprising an anionic detergent compound, which will adequately disperse in the wash water.
Laundry detergent compositions which further include a fabric softener to provide softening or conditioning of fabrics in the wash cycle of the laundering operation are well-known and described in the patent literature. See, for example, U.S. Pat. No. 4,605,506 (Wixon); U.S. Pat. No. 4,818,421 (Boris) et al. and U.S. Pat. No. 4,569,773 (Ramachandran et al.) and U.S. Pat. No. 4,851,138. U.S. Pat. No. 5,972,870 (Anderson) describes a multi-layered laundry tablet for washing which may include a detergent in the outer layer and a fabric softener, or water softener or fragrance in the inner layer.
These types of multi-benefit products suffer from a common drawback, namely, there is an inherent compromise which the user necessarily makes between the cleaning and softening benefits provided by such products as compared to using a separate detergent composition solely for cleaning in the wash cycle and a separate softening composition solely for softening in the rinse cycle. That is, the user of such detergent softener compositions does not have the ability to independently adjust the amount of detergent and softener added to the wash cycle of a machine in response to the cleaning and softening requirements of the particular wash load.
Some attempts have been made in the art to develop wash cycle active fabric softeners, typically in powder form. However, these type products are characterised by the same inconvenience inherent with the use of powered detergents, namely, problems of handling, caking in the container or wash cycle dispenser, and the need for a dosing device to deliver the desired amount of active softener material to the wash water.
The use of a unit dose fabric softening composition contained in a water soluble container such as a sachet offers numerous advantages. To be effective, the unit dose fabric softening compositions, contained in a sachet, must be able to disperse in the wash liquor in a short period of time to avoid any residue at the end of the wash cycle.
Typically, the wash cycle time can be as short as 12 minutes and as long as 90 minutes (in typical European washers) depending on the type of washer and the wash conditions. Therefore, the water-soluble sachet must be soluble in the wash liquor before the end of the cycle.
Liquid unit dose softeners have been disclosed in our co-pending applications WO-A-02/102955, WO-A-02/102956 and GB 0222964.9.